/Engine/Source/Editor/MeshPaint/Public/TexturePaintHelpers.h
Makes sure that the render target is ready to paint on
static void SetupInitialRenderTargetData ( [UTexture2D](API\Runtime\Engine\Engine\UTexture2D) * InTextureSource, [UTextureRenderTarget2D](API\Runtime\Engine\Engine\UTextureRenderTarget2D) * InRenderTarget )